It is known to mass produce housing units with iron or aluminum plank formwork or falsework constituting concrete molds and which are joined at the construction site by means of insertable connecting elements to assemble the molds.
Plank mold-forming elements are thus assembled to permit the formation of a lower part of the structure and when the concrete has hardened sufficiently, the connecting elements are removed to allow disassembly of the formwork and new erection thereof to provide an upper portion of the structure which may include the roof, or upon which the roof can be fabricated from different materials.
Conventional plank-type concrete formwork has several drawbacks:
Firstly, the planks can be relatively heavy so that plank formations of large dimensions can only be assembled with machinery and equipment for manipulating the planks.
Secondly, the method and means for connecting the plank forms at their edges can be complex and can require the use of specialized personnel. Moreover, if the interconnection is not proper, the concrete structures which result may have an unsatisfactory appearance or can result in cracks in the concrete structure which may be detrimental to the building unit.
Thirdly, the weight and dimensions of prior art formations can cause them to deform, thereby making use of these elements difficult and preventing them from being reused a sufficient number of times. This can greatly increase the final cost of structures made using such elements. When the parts of the concrete formwork deform, attempts can be made to repair them, but this can create new problems since the surfaces which result generally are not sufficiently smooth. Also, the straightening operation increases the cost and is time consuming.
Earlier systems of erecting concrete structures utilizing molds formed by planks of the type described is that, once the wall molds have been assembled and the concrete poured and hardened, the fabrication of a new mold for the roof is required when it is to be made of concrete. When, however, the roof is to be made of other materials, considerable time must pass before the roof is erected.